The invention relates generally to power-driven conveyors and, more particularly, to conveyors, such as belt conveyors, with selectively actuated advancing rollers.
Conveyor belts with rollers provide material-handling functions such as product diversion, sortation, singulation, separation, orientation, and acceleration. The belts typically include an array of rollers arranged in rows and columns. The rollers extend through the thickness of the belt to support products on one side and to engage bearing surfaces underlying the belt on the other side along a carryway. As the belt advances, the rollers rotate as they roll on the bearing surfaces and propel supported products in the direction of the rollers' rotation. The orientation of the rollers' axes of rotation determines the direction in which products are propelled atop the belt. The bearing surfaces may be formed by a continuous pan across the entire width of the belt or by parallel, linear flat bearing surfaces arranged under each column of rollers. In some applications, the peripheries of actuating rollers serve as bearing surfaces on which the belt rollers roll as the belt advances. These bearing surfaces may all be arranged to move into and out of contact with the belt rollers to selectively actuate the rollers. The bearing surfaces may be moved by pneumatic cylinders or other mechanical devices. Because, in some cases, the bearing surfaces are heavy, moving them rapidly into and out of contact with the belt rollers may require a complex framework and a lot of power. Furthermore, even though the belt rollers roll on the bearing surfaces, the contact is not frictionless and, so, increases the tension in the belt and reduces roller life.
Thus, there is a need to reduce the shortcomings associated with rollers that roll on bearing surfaces and support products.